Ionospheric Responses to CME‐ and CIR‐Driven Geomagnetic Storms Along 30°E–40°E Over the African Sector From 2001 to 2015

Abstract

In this paper, we present the responses of the ionospheric total electron content (TEC) to coronal mass ejection (CME)‐ and corotating interaction region (CIR)‐driven storms using stations that lie within 30°E–40°E geographic longitude in middle, low, and equatorial latitudes over the African sector. CIR‐driven storms are generally weak (−50 nT < Dst < −25 nT) to moderate (−100 nT < Dst < −50 nT) in intensity, while CME‐driven storms are often associated with the intense (Dst < −100 nT) geomagnetic storms. CIR‐driven storms have long recovery phase as compared to CME‐driven storms. CME‐ and CIR‐driven storms were classified based on the features of proton temperature, magnetic field, solar wind speed, and proton density. The storm periods analyzed occurred during the period 2001–2015, which covers part of solar cycles 23 and 24. Disturbance storm time (Dst) ≤ −30 nT and Kp ≥ 3 indices were used simultaneously to identify the storm periods considered. The total number of CME‐ and CIR‐driven storms identified was 148 and 167, respectively. However, due to lack of TEC data, the number of CME‐ and CIR‐driven storms considered for the middle‐latitude, low‐latitude, and equatorial latitude stations are different for different regions. TEC data used in this study was derived from the Global Navigation Satellite System observations. The statistical analysis of ionospheric storm effects were compared over middle, low, and equatorial latitudes in the African sector for the first time. Negative ionospheric storm effects occurred only during CME‐driven storms over midlatitude stations and were more prevalent in summer. For the low and equatorial latitudes, negative ionospheric storm effects were observed during both CME‐ and CIR‐driven storms. Our analysis has shown that positive ionospheric storm effects were more prevalent over middle, low, and equatorial latitudes during both CME‐ and CIR‐driven storms. A significant number of cases where the electron density changes remained within the background variability during storm conditions were observed over the low‐latitude stations compared to other latitude regions.

Spatio‐Temporal Evolution of Global Ionospheric Storm Drivers and Hemispherical Asymmetry During 17–18 March 2015 Geomagnetic Storm

“…In this work, the five IQDs of March 2015 used are March 10, 30, 05, 14, and 09. The dvTEC% beyond the range of ±45% is considered as GMS-driven Ionospheric storm effect (Matamba & Habarulema, 2018).…”

Space Weather Effects on the Earth’s Upper Atmosphere: Short Report on Ionospheric Storm Effects at Middle Latitudes

“…However, interest in the solar cycle effect on the ionospheric storm time response was greatly revived in the years following the deep 2008-2009 solar minimum, and probably the low activity solar cycle 24. Shortcomings in ionospheric prediction capabilities during this deep solar minimum that were identified for all types of model formulations (from empirical to physics-based ones), the investigation of the long-term behavior of the ionospheric disturbances in solar cycle 24, and the analysis of specific storm events through multiinstrument data and models simulations, revealed the significant impact of the geomagnetic storm drivers in the observed effects [39,42,[46][47][48][49][50][51][52]. Although it is known that ionospheric storm effects of significant intensity are observed even during solar minimum years, there is now some evidence that the ionospheric response to CIR/HSSs-driven storms may be different than the one to CME-driven events.…”

“…Similar results have also been reported at several occasions for middle latitudes. As indicative cases, we note: Buresova et al [39] reported mainly positive disturbances in terms of the peak electron density under the occurrence of CIR-generated storms that occurred in the low solar activity years 2008-2009, with no significant changes in hmF2 in several cases; Burns et al [48] found positive effects of geomagnetic storms in the peak electron density of the ionospheric F2 layer in the main storm days during CIR/HSSsdriven events; Dimitriev et al [49] and Verkhoglyadova et al [50,51] revealed the close relationship between the positive ionospheric storms and recurrent geomagnetic activity; Matamba and Habarulema [52] concluded that positive ionospheric storm effects in terms of GPS-derived TEC were more prevalent over middle, low and equatorial latitude stations during both CME-and CIR-driven storms, while negative ionospheric storm effects occurred only during CME-driven storms at the considered Southern and Northern Hemisphere middle latitudes. Similar results have also been reported at several occasions for middle latitudes.…”

Development and Evaluation of Near‐Real Time TEC and Ancillary Products for SANSA Space Weather

“…The Sun releases particles into the heliosphere during Coronal Mass Ejection (CME) that may travel from the Sun to the Earth. The strong/major geomagnetic storm that occur following the CME may cause a combination of positive and negative ionospheric storm effects on TEC over the mid‐latitude region (Matamba & Habarulema, 2018, 2021; Matamba et al., 2015, 2016). The daytime positive ionospheric storm effects may be attributed to the E × B drift of magnetospheric origin (Mannucci & Tsurutani, 2018).…”